Instructions
Go to the PlayStation Store on your PlayStation3 game console. You can access the store through the PlayStation Network section on the XMB interface.
Select "Browse All Games" and scroll down until you find "PlayStation3 content."
Browse games that begin with the letters J through L.
Select "LittleBigPlanet" to view the downloadable content available to you. Select the "Halloween Mask" costume from the game catalog.
Download and install the Halloween Costume mask so it will be available the next time you play the game.